394 research outputs found
Nonlinear Abel type integral equation in modelling creep crack propagation
Copyright @ 2011 Birkhäuser BostonA nonlinear Abel-type equation is obtained in this paper to model creep crack time-dependent propagation in the infinite viscoelastic plane. A finite time when the integral equation solution becomes unbounded is obtained analytically as well as the equation parameters when solution blows up for all times. A modification to the Nyström method is introduced to numerically solve the equation and some computational results are presented
A Compact Gas Cerenkov Detector with Novel Optics
We discuss the design and performance of a threshold Cerenkov counter for
identification of charged hadrons. The radiator is pressurized gas, which is
contained in thin-walled cylindrical modules. A mirror system of novel design
transports Cerenkov photons to photomultiplier tubes. This system is compact,
contains relatively little material, and has a large fraction of active volume.
A prototype of a module designed for the proposed CLEO III detector has been
studied using cosmic rays. Results from these studies show good agreement with
a detailed Monte Carlo simulation of the module and indicate that it should
achieve separation of pions and kaons at the 2.5-3.0sigma level in the momentum
range 0.8-2.8 GeV/c. We predict performance for specific physics analyses using
a GEANT-based simulation package.Comment: Submitted to NIM. 23 pages, 11 postscript figures. Postscript file is
also available at http://w4.lns.cornell.edu/public/CLNS/199
Working time flexibility components and working time regimes in Europe: using company-level data across 21 countries
Working time ?exibility comprises a wide variety of arrangements, from part-time,
overtime, to long-term leaves. Theoretical approaches to grouping these arrangements
have been developed, but empirical underpinnings are rare. This article investigates
the bundles that can be found for various ?exible working time arrangements, using the
Establishment Survey on Working Time and Work–Life Balance, 2004/2005, covering 21
EU member states and 13 industries. The results from the factor analyses con?rmed that
working time arrangements can be grouped into two bundles, one for the employee-centred
arrangements and second for the employer-centred arrangements, and that these two
bundles are separate dimensions.Wealso tested the stability of the factor analysisoutcome,
showing that although we ?nd some deviations from the pan-Europe and pan-industry
outcome, the naming of the components as ?exibility for employees and ?exibility for
employers can be considered rather stable. Lastly, we ?nd three country clusters for the 21
European countries using the bundle approach. The ?rst group includes the Northern
European countries along side Poland and Czech Republic, the second group the
continental European countries with UK and Ireland, and lastly, the southern European
countries with Hungary and Slovenia
The change in productivity of Chinese state enterprises, 1983–1987
This study estimates the change in productivity of Chinese state enterprises during 1983–1987 using a panel data set of 403 firms. A new approach to productivity measurement is used. Under this approach, the production functions can differ arbitrarily across firms, important given the heterogeneity of the sample. The resulting coefficients estimate the marginal products of each factor as well as overall productivity growth. The results suggest Chinese productivity increased by 4.6% per year, with about half of this growth due to the rapidly improving education of the labor force.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47564/1/11123_2005_Article_BF01073492.pd
Interplay of quantum magnetic and potential scattering around Zn or Ni impurity ions in superconducting cuprates
To describe the scattering of superconducting quasiparticles from
non-magnetic (Zn) or magnetic (Ni) impurities in optimally doped high T
cuprates, we propose an effective Anderson model Hamiltonian of a localized
electron hybridizing with -wave BCS type superconducting
quasiparticles with an attractive scalar potential at the impurity site. Due to
the strong local antiferromagnetic couplings between the original Cu ions and
their nearest neighbors, the localized electron in the Ni-doped materials is
assumed to be on the impurity sites, while in the Zn-doped materials the
localized electron is distributed over the four nearest neighbor sites of the
impurities with a dominant symmetric form of the wave function.
With Ni impurities, two resonant states are formed above the Fermi level in the
local density of states at the impurity site, while for Zn impurities a sharp
resonant peak below the Fermi level dominates in the local density of states at
the Zn site, accompanied by a small and broad resonant state above the Fermi
level mainly induced by the potential scattering. In both cases, there are no
Kondo screening effects. The local density of states and their spatial
distribution at the dominant resonant energy around the substituted impurities
are calculated for both cases, and they are in good agreement with the
experimental results of scanning tunneling microscopy in
BiSrCaCuO with Zn or Ni impurities, respectively.Comment: 24 pages, Revtex, 8 figures, submitted to Physical Review B for
publication. Sub-ject Class: Superconductivity; Strongly Correlated Electron
The role of self-gentrification in sustainable tourism: Indigenous entrepreneurship at Honghe Hani Rice Terraces World Heritage Site, China
This article examines three forms of tourism gentrification occurring within the newly inscribed (2013) Honghe Hani Rice Terraces UNESCO World Heritage Site in Yunnan, China. The indigenous Hani and Yi communities who populate this remote mountainous area, possess distinct cultural practices that have supported the rice terrace ecosystem for centuries. This article draws on interviews and non-participant observation conducted with inhabitants and newcomers to analyse the types of gentrification occurring within the site. We argue that indigenous cultural practices, and consequently rice cultivation in the area, are threatened by gentrifier-led and state-led gentrification combined with high levels of outward migration of indigenous persons. This could pose a significant threat to the sustainability of tourism at this site and may ultimately compromise the site’s World Heritage Status. In the midst of these dangers, some indigenous people are shown to be improving their socioeconomic standing – and becoming “middle class” or “gentry” – particularly through adopting entrepreneurial strategies gleaned from their encounters with outside-gentrifiers and tourists. This article proposes the concept of “self-gentrification” as a way to describe individuals who seek to improve themselves and their own community, while under threat of gentrification
Gravitational Lensing by Black Holes
We review the theoretical aspects of gravitational lensing by black holes,
and discuss the perspectives for realistic observations. We will first treat
lensing by spherically symmetric black holes, in which the formation of
infinite sequences of higher order images emerges in the clearest way. We will
then consider the effects of the spin of the black hole, with the formation of
giant higher order caustics and multiple images. Finally, we will consider the
perspectives for observations of black hole lensing, from the detection of
secondary images of stellar sources and spots on the accretion disk to the
interpretation of iron K-lines and direct imaging of the shadow of the black
hole.Comment: Invited article for the GRG special issue on lensing (P. Jetzer, Y.
Mellier and V. Perlick Eds.). 31 pages, 12 figure
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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